Patent Literature 1 (Japanese Patent No. 3833573) describes related art of the hybrid working machine. Patent Literature 1 discloses “a hybrid construction machine capable of driving a hydraulic pump by use of an engine and a motor-generator, the hydraulic construction machine including: pump output calculation means which calculates the output of the hydraulic pump; revolution speed setting means which sets a revolution speed of the engine; threshold value setting means which sets a threshold value at which the motor-generator is switched between motor capability and generator capability, the threshold value being set as a function on the engine revolution speed set by the revolution speed setting means; comparison means which compares the threshold value set by the threshold value setting means, with the hydraulic pump output calculated by the pump output calculation means; and switching control means which controls switching of the capabilities of the motor-generator in accordance with a result of the comparison performed by the comparison means.”